Polyphenylene ether resin composition

ABSTRACT

The resin composition of the present invention comprises (A) a resin composition comprising a polyphenylene ether resin or a polyphenylene ether resin and a polystyrene resin and (B) a phosphazene compound having an acid value of less than 0.5. This resin composition contains no halogen compounds and hence is environmentally preferred, and furthermore is excellent in electrical characteristics, heat resistance and mechanical properties, causes substantially no problems such as smoking during injection molding and desposition of flame-retardants on the mold, and has high flame retardancy.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/JP01/07610 which has an Internationalfiling date of Sep. 3, 2001, which designated the United States ofAmerica.

TECHNICAL FIELD

The present invention relates to a resin composition excellent in flameretardancy and preferred for environmental protection.

BACKGROUND ART

For flame-retardation of flammable synthetic resins, there have beengenerally employed flame-retardation methods such as addition ofhalogen-containing compounds and antimony trioxide, etc. However, theseconventional flame-retardation methods are not desirable forenvironmental health and there is a demand to improve them in thisrespect.

On the other hand, for flame-retardation of polyphenylene ether resinsor mixed resins thereof with styrene resins or polycarbonate resins ormixed resins thereof with styrene resins, halogen-containing compoundshave not been used and there have been used organic phosphoric acidesters, for example, monophosphoric acid esters such as triphenylphosphate, cresyl diphenyl phosphate and tricresyl phosphate, condensedphosphoric acid esters of resorcinol or bisphenol A, a phenol compoundand phosphoric acid, etc. However, these resin compositions haveproblems such as deterioration in heat resistance and physicalproperties, water absorption at high temperature and high humidity,occurrence of smoke during injection molding, and deposition offlame-retardants onto the mold. Among them, condensed phosphoric acidesters obtained from resorcinol, 2,6-dimethylphenol and phosphoric acidare considered to be less problematic.

Furthermore, as for the flame-retardation of polyphenylene ether resinsor mixed resins thereof with styrene resins, resin compositionscontaining phosphazene compounds such as phenoxyphosphazene asflame-retardants are disclosed in JP-B-3-73590, JP-A-9-71708,JP-A-9-183864, JP-A-11-181429 and WO 00/09518. However, even thoughthese resin compositions are larger in phosphorus content as comparedwith the above resin compositions containing organic phosphoric acidester flame-retardants, the former resin compositions are insufficientin flame retardancy and sometimes cause deterioration of electricalcharacteristics inherent to resins and formation of deposits onto themold during molding, and thus they are not considered to be effectiveflame-retardants.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a resin compositionwhich contains no halogen-containing compounds, is excellent in heatresistance, mechanical characteristics and electrical characteristics,has substantially no problems such as occurrence of smoke duringinjection molding and deposition of flame-retardants on the mold, ispreferred for environmental health, and has high flame retardancy.

As a result of intensive research conducted by the present inventors inan attempt to attain the above object, it has been found that the aboveobject can be attained by using a resin composition containing a resincomposition comprising a polyphenylene ether resin or a polyphenyleneether resin and a polystyrene resin and a specific phosphazene compound.Thus, the present invention has been accomplished.

That is, the present invention relates to the following inventions.

[1] A resin composition containing (A) a resin composition comprising apolyphenylene ether resin or a polyphenylene ether resin and apolystyrene resin and (B) a phosphazene compound having an acid value ofless than 0.5.

[2] A resin composition as mentioned in the above [1], wherein the acidvalue of the phosphazene compound is less than 0.3.

[3] A resin composition as mentioned in the above [1] or [2], whereinthe phosphazene compound is a phenoxyphosphazene compound.

[4] A resin composition as mentioned in the above [1] or [2], whereinthe phosphazene compound has a cyclic structure.

[5] A resin composition as mentioned in the above [1] or [2], whereinthe phosphazene compound is a phenoxyphosphazene compound having acrosslinked structure.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be specifically explained below.

As the polyphenylene ether resins used in the present invention, thereare used homopolymers or copolymers having the repeating unitsrepresented by the following general formulas (I) and/or (II):

(where R1, R2, R3, R4, R5 and R6 each independently represent an alkylgroup of 1-4 carbon atoms, an aryl group, halogen or hydrogen, with aproviso that R5 and R6 do not simultaneously represent hydrogen).

Representative examples of homopolymers of the polyphenylene etherresins are poly(2,6-dimethyl-1,4-phenylene) ether,poly(2-methyl-6-ethyl-1,4-phenylene) ether,poly(2,6-diethyl-1,4-phenylene) ether,poly(2-ethyl-6-n-propyl-1,4-phenylene) ether,poly(2,6-di-n-propyl-1,4-phenylene) ether,poly(2-methyl-6-n-butyl-1,4-phenylene) ether,poly(2-ethyl-6-isopropyl-1,4-phenylene) ether,poly(2-methyl-6-chloroethyl-1,4-phenylene) ether,poly(2-methyl-6-hydroxyethyl-1,4-phenylene) ether,poly(2-methyl-6-chloroethyl-1,4-phenylene) ether, etc.

Of these homopolymers, poly(2,6-dimethyl-1,4-phenylene) ether ispreferred. Especially preferred are polyphenylene ethers having as apartial structure a 2-(dialkylaminomethyl)-6-methylphenylene ether unit,a 2-(N-alkyl-N-phenylaminomethyl)-6-methylphenylene ether unit, or thelike as disclosed in JP-A-63-301222.

The polyphenylene ether copolymers should be understood here to meancopolymers having a phenylene ether structure as a main monomer unit.Examples of them are a copolymer of 2,6-dimethylphenol and2,3,6-trimethylphenol, copolymer of 2,6-dimethylphenol and o-cresol,copolymer of 2,6-dimethylphenol, 2,3,6-trimethylphenol and o-cresol,etc.

In the present invention, a part or all of the polyphenylene etherresins can be modified polyphenylene ether resins modified with anunsaturated carboxylic acid or a derivative thereof. These modifiedpolyphenylene ether resins are disclosed in JP-A-2-276823,JP-A-63-108059 and JP-A-59-59724, and they are produced, for example, bymelt kneading a polyphenylene ether resin with an unsaturated carboxylicacid or a derivative thereof to react them in the presence or absence ofa radical initiator. Alternatively, they are produced by dissolvingpolyphenylene ether and an unsaturated carboxylic acid or a derivativethereof in an organic solvent in the presence or absence of a radicalinitiator and reacting them in a solution.

Examples of the unsaturated carboxylic acids or derivatives thereofinclude maleic acid, fumaric acid, itaconic acid, halogenated maleicacid, cis-4-cyclohexene-1,2-dicarboxylic acid,endo-cis-bicyclo(2,2,1)-5-heptene-2,3-dicarboxylic acid, and anhydrides,esters, amides, imides, etc. of these dicarboxylic acids, and,furthermore, acrylic acid, methacrylic acid and esters, amides, etc. ofthese monocarboxylic acids. Moreover, there may also be used compoundswhich are saturated carboxylic acids, but are per se heat decomposed atthe reaction temperature in production of the modified polyphenyleneether and can become the derivatives usable in the present invention.Examples of the compounds are malic acid, citric acid, etc. These may beused each alone or in combination of two or more.

Next, the styrene resins used in the present invention are polymersobtained by polymerizing a styrene compound or a styrene compound and acompound copolymerizable with a styrene compound in the presence orabsence of a rubber-like polymer.

Examples of the styrene compounds include styrene, β-methylstyrene,2,4-dimethylstyrene, monochlorostyrene, p-methylstyrene,p-tert-butyl-styrene, ethylstyrene, etc. Styrene is most preferred.Examples of the compounds copolymerizable with the styrene compoundsinclude methacrylic acid esters such as methyl methacrylate and ethylmethacrylate; unsaturated nitrile compounds such as acrylonitrile andmethacrylonitrile; acid anhydrides such as maleic anhydride; etc. Theamount of the copolymerizable compounds is preferably not more than 20%by weight, more preferably not more than 15% by weight based on thetotal amount of the copolymerizable compound and the styrene compound.

The rubber-like polymers include, for example, conjugated diene rubbers,copolymers of conjugated diene and aromatic vinyl compound,ethylene-propylene copolymer rubbers, etc. Specifically, polybutadieneand styrene-butadiene copolymer are especially preferred. In the case ofusing unsaturated rubber-like polymers, it is preferred to use partiallyhydrogenated rubbers.

Examples of the styrene resins include polystyrene and rubber-reinforcedpolystyrene, styrene-acrylonitrile copolymer (AS resin) andrubber-reinforced styrene-acrylonitrile copolymer (ABS resin), and otherstyrene copolymers. Polystyrene and rubber-modified polystyrene areparticularly preferred.

The phosphazene compounds used in the present invention are those whichhave a cyclic or straight chain structure represented by the followinggeneral formula (III):

(where R's each independently represent an aliphatic or aromatic groupof 1-20 carbon atoms, and n is an integer of 3 or more). Those whichhave a cyclic structure are preferred. It is especially preferred to usephenoxyphosphazene compounds having a six-membered ring where n=3,phenoxyphosphazene compounds having an eight-membered ring where n=4,and mixtures thereof.

Furthermore, these compounds may be cross-linked with a crosslinkinggroup selected from the group consisting of a phenylene group,biphenylene group and a group represented by the following formula:

(where X represents —C(CH₃)₂-, —SO₂-, —S— or —O—) by the methoddisclosed in JP-A-11-181429 or WO 00/09518. These phosphazene compoundshaving a crosslinked structure (crosslinked phosphazene compounds) areproduced specifically by reacting a dichlorophosphazene oligomer with analkali metal salt of phenol and an alkali metal salt of an aromaticdihydroxy compound. These alkali metal salts are added to thedichlorophosphazene oligomer slightly in excess of the stoichiometricamount.

The phosphazene compounds represented by the formula (III) are knowncompounds and are disclosed, for example, in James E. Mark, Harry R.Allcock, Robert West, “Inorganic Polymers”, Pretice-Hall International,Inc., 1992, p61-p140.

As reference literatures which disclose examples of preparation of thesephosphazene compounds, mention may be made of JP-B-3-73590,JP-A-9-71708, JP-A-9-183864, JP-A-11-181429, and WO 00/09518.

It is essential that the phosphazene compounds used in the presentinvention have an acid value of less than 0.5, and the acid value ispreferably less than 0.3, more preferably less than 0.15. The acid valueis used here to mean a value shown by the mg of potassium hydroxiderequired for neutralizing the acidic component contained in 1 g of asample, which is in accordance with JIS K2501. The acid value can becontrolled by repeatedly washing and purifying the prepared crudephosphazene compound. Specifically, the crude phosphazene compound ispurified by repeated washing and dehydration with a dilute aqueous acidor alkali solution and additionally washing and dehydration with a mixedliquid of water and methanol. By increasing the number of times ofwashing, a phosphazene compound of smaller acid value can be obtained.Furthermore, the acid value can be efficiently reduced by purifying theprepared phosphazene compound by allowing the phosphazene compound tocontact with one or more adsorbents selected from the group consistingof activated carbon, silica gel, activated alumina, activated clay,molecular sieves and polymer-type adsorbents. The phosphazene compoundsubjected to the adsorbent treatment is superior in quality to thephosphazene compound subjected to washing with a neutral, acidic oralkaline aqueous solution. When the phosphazene compound subjected tothe adsorbent treatment is used, the flame retardancy and electricalcharacteristics of the resin compositions are improved, and problemssuch as decomposition of resin when processed at high temperatures,occurrence of smoke during injection molding and deposition onto moldscan be mostly solved.

In the present invention, for the treatment of a phosphazene compoundwith adsorbent, any methods can be employed as long as the adsorbent andthe phosphazene compound can contact with each other. For example, theadsorbent and the phosphazene compound may be mixed in the same tank(batch type) or the adsorbent may be packed in a column so as to passthe phosphazene compound through the column. In the case of the batchmethod, the amount of the adsorbent used is not particularly limited,and can be selected from a wide range depending on various conditionssuch as the kind and amount of the phosphazene compound and the kind ofadsorbent, etc. and the amount is usually 1-30 parts by weight,preferably 2-25 parts by weight based on 100 parts by weight of thephosphazene compound. If the amount of the adsorbent is less than 1 partby weight, the effect of reduction of acid value may be insufficient,and if it excessively exceeds 30 parts by weight, not only theimpurities, but also the phosphazene compound are adsorbed, which mayresult in reduction of the yield. On the other hand, when the treatmentis carried out by packing the adsorbent in a column, the amount of theadsorbent used is not limited. The column is prepared with a packingmaterial in such an amount that problems are not caused in operation ofthe column. A column may be used continuously and when the adsorbabilitylowers, the packing material may be changed or regenerated.

The contact of the phosphazene compound with the adsorbent may becarried out where the phosphazene compound is molten with heating, or asolvent may be used. The concentration of the phosphazene compound inthe case of using a solvent has no particular limitation, but ispreferably 1-90% from the point of ease in operation. The reactiontemperature in the case of using a solvent has no particular limitationas long as the phosphazene compound dissolves at that temperature, butit is preferred that the reaction temperature is generally in the rangeof 0° C. to the boiling point of the solvent used. On the other hand, inthe case of the phosphazene compound being molten with heating, thereaction temperature is preferably about 200° C. or lower. Furthermore,the reaction time has no special limitation because no adverse effect iscaused even if the phosphazene compound contacts with the adsorbent fora long time, but is preferably 5 minutes to 12 hours.

The solvents used here may be any solvents as long as they can dissolvethe phosphazene compound and do not hinder the action of the adsorbent.For example, mention may be made of organic solvents, e.g., aromatichydrocarbons such as benzene, toluene and xylene, halogenated aromatichydrocarbons such as monochlorobenzene and dichlorobenzene, ketones suchas acetone, methyl ethyl ketone and methyl isobutyl ketone, alcoholssuch as methanol, ethanol, n-propanol, isopropanol, n-butanol andtert-butanol, esters such as methyl formate, ethyl formate, propylformate, butyl formate, methyl acetate, ethyl acetate, propyl acetateand butyl acetate, ethers such as diethyl ether, diisopropyl ether,dibutyl ether, tetrahydrofuran, dioxane and trioxane,nitrogen-containing hydrocarbons such as acetonitrile, benzonitrile andpyridine, etc. These solvents may be used each alone or in admixture oftwo or more.

In the present invention, the phosphazene compound is preferably aphenoxyphosphazene compound, especially preferably a phenoxyphosphazenecompound having a crosslinked structure.

In the present invention, if the acid value of the phosphazene compoundis 0.5 or more, the flame retardancy of the resin composition is low,and the phosphazene compound is inferior to organic phosphoric acidester flame-retardants with respect to physical properties of the resincomposition. The resin composition containing the phosphazene compoundhaving an acid value of less than 0.5 is excellent not only in flameretardancy, but also in electrical characteristics such as relativedielectric constant and dielectric loss tangent. Moreover, a phosphazenecompound having an acid value of 0.5 or more may damage the propertiesinherent to the resin due to hydrolysis or the like in reuse of theresin, placing restrictions on reuse. Higher hydrolyzability suggeststhat when the resin is discarded, it may dissolve into water or soil,and this causes environmental problems.

In the present invention, as for the mixing ratio of (B) the phosphazenecompound to (A) the resin composition comprising a polyphenylene etherresin or a polyphenylene ether resin and a polystyrene resin, a ratiowhich provides the desired flame retardancy may be optionally selected,but it is restricted by fluidity during the molding process, heatresistance, mechanical characteristics or economical efficiency of thecomposition. The amount of the phosphazene compound (B) is preferably inthe range of 1-30 parts by weight based on 100 parts by weight of theresin composition (A) comprising a polyphenylene ether resin or apolyphenylene ether resin and a polystyrene resin.

A composite of high strength excellent in fluidity and heat resistancecan be obtained by further adding inorganic fillers such as glassfibers, glass flakes, kaolin clay and talc or other fibrous reinforcingmaterials to the resin composition of the present invention.Furthermore, as impact resistance imparting agents, there may besuitably used thermoplastic elastomers, e.g., rubber-like polymers suchas styrene-butadiene block copolymer, styrene-isoprene block copolymerand hydrogenation products thereof.

In order to impart other characteristics, there may be further added tothe resin composition of the present invention, in a range that does notdamage the effects of the present invention, other additives, e.g.,plasticizers, stabilizers such as antioxidants and ultravioletabsorbers, antistatic agents, releasing agents, dyes and pigments orother resins. Moreover, the flame retardancy can further be improved byadding known various flame-retardants or flame retarding aids such asalkali metal hydroxides or alkaline earth metal hydroxides such asmagnesium hydroxide and aluminum hydroxide containing water ofcrystallization, zinc borate compounds, zinc stannate compounds, andinorganic silicon compounds such as silica, kaolin clay and talc to theresin composition.

The method for producing the resin composition of the present inventionis not particularly limited, and the composition can be produced bykneading with kneading machines such as extruders, heating rolls,kneaders and Banbury mixers. Among them, kneading by extruders ispreferred from the point of productivity. The kneading temperature candepend on the preferred processing temperature of the base resin, and isin the range of 200-360° C., preferably 240-320° C. as a standard.

EXAMPLE

The present invention will be explained by the following examples, withpreparation examples and reference examples of the phosphazenecompounds. The present invention shall not be limited to these examples.

The components used in the examples and the comparative examples are asfollows.

(A-1) Polyphenylene ether (PPE)

PPE: Unmodified poly-2,6-dimethyl-1,4-phenylene ether having a η sp/c of0.54 measured in a chloroform solution at 30° C.

(A-2) Rubber-reinforced polystyrene (HIPS)

HIPS: A rubber-reinforced polystyrene having a rubber content of 9%, a ηsp/c of matrix polystyrene of 0.64 measured in a toluene solution at 30°C., and a volumetric average rubber particle diameter of 1.5 μm.

(B) Phenoxyphosphazene compound

Preparation Example 1-1: Preparation of Phenoxyphosphazene Compound

113.0 Grams (1.2 moles) of phenol was charged in a four-necked flask of1 liter equipped with a stirrer, a thermometer and a reflux condenser,and 400 mL of tetrahydrofuran (THF) was added thereto to carry outuniform dissolution. Then, 26.4 g of metallic sodium was added theretoat 25° C. or lower, and after completion of the addition, thetemperature was raised to 63° C. over a period of 1 hour, followed bycontinuation of stirring at 63-68° C. for 6 hours to prepare a sodiumphenolate solution.

In parallel with the above reaction, 58.0 g (0.5 unit mole) of a mixtureof hexachlorocyclo-triphosphazene and octachlorocyclotetraphosphazene(hexachlorocyclotriphosphazene (trimer); 62%,octachlorocyclotetraphosphazene (tetramer); 38%) was dissolved in 250 mLof THF in a 2L four-necked flask, and to the resulting solution whilestirring at 25° C. or lower was added dropwise the sodium phenolatesolution prepared above. After completion of the addition, reaction wascarried out with stirring at 71-73° C. for 12 hours. After completion ofthe reaction, the reaction mixture was concentrated and re-dissolved in500 mL of toluene, followed by carrying out water washing, washing witha 5% aqueous sodium hydroxide solution, washing with a 5% aqueoushydrochloric acid solution, washing with a 5% aqueous sodium bicarbonatesolution, and water washing. To this toluene solution was added 5 g ofsilica gel (tradename: WAKO GEL C-200 manufactured by Wako Pure ChemicalIndustries, Ltd.), followed by stirring at room temperature for 1 hour.After the silica gel was filtered off, the organic layer wasconcentrated under reduced pressure. The resulting product was vacuumdried with heating at 80° C. for 11 hours under 4 hPa or lower to obtain104 g of a white solid.

The resulting phenoxyphosphazene compound had an acid value of 0.01 mgKOH/g and contained hydrolyzable chlorine of 0.03% or less. The meltingpoint (Tm) according to TG/DTA analysis was 108° C., the decompositionstarting temperature was 323° C., and the 5% weight loss temperature was335° C.

Preparation Example 1-2: Preparation of Phenoxyphosphazene Compound

A phenoxyphosphazene compound was prepared in the same manner as inPreparation Example 1-1, except that the amount of the silica gel usedfor the post-treatment after completion of the reaction was 1 g. Theresulting phenoxyphosphazene compound had an acid value of 0.3 mg KOH/g.

Reference Example 1: Preparation of Phenoxyphosphazene Compound

A phenoxyphosphazene compound was prepared in the same manner as inPreparation Example 1-1, except that the treatment with silica gel wasnot carried out in the post-treatment after completion of the reaction,thereby obtaining 109 g of a slightly yellow solid. The resultingphenoxyphosphazene compound had an acid value of 0.77 mg KOH/g andcontained hydrolyzable chlorine of 0.08%. The melting point (Tm)according to TG/DTA analysis was 106° C., the decomposition startingtemperature was 321° C., and the 5% weight loss temperature was 333° C.

Preparation Example 2: Preparation of Phenoxyphosphazene Compound HavingCrosslinked Structure Given by 2,2-bis(p-oxyphenyl)isopropylidene Group

56.5 Grams (0.6 mole) of phenol and 500 mL of toluene were charged in a1 L four-necked flask, and 0.55 gram atom (12.6 g) of metallic sodiumchips were added thereto under stirring while keeping the inner liquidtemperature at 25° C., followed by stirring at 90-113° C. for 8 hoursuntil the metallic sodium completely disappeared, thereby to prepare asodium phenolate solution.

In parallel with the above reaction, 57.1 g (0.25 mole) of bisphenol A,103.5 g (1.1 mole) of phenol and 700 mL of THF were charged in a 3 Lfour-necked flask, and 1.6 gram atom (11.1 g) of metallic lithium chipswere added thereto under stirring while keeping the inner liquidtemperature at 25° C., followed by stirring at 63-68° C. for 8 hoursuntil the metallic lithium completely disappeared. To this slurrysolution was added dropwise 1.0 mole (115.9 g) of dichlorophosphazeneoligomer (concentration: 37%; chlorobenzene solution: 313 g;composition: a mixture of 70% of trimer, 19% of tetramer, 8% of pentamerand hexamer, 2% of heptamer, and 1% of octamer or higher polymers) understirring while keeping the inner liquid temperature at 20° C. or lower,followed by carrying out the reaction at 80° C. for 2 hours. Then, theseparately prepared sodium phenolate solution was added under stirringwhile keeping the inner liquid temperature at 20° C., followed bycarrying out the reaction at 80° C. for 5 hours.

After completion of the reaction, the reaction mixture was concentratedto remove THF, and 1 L of toluene was further added. The resultingtoluene solution was washed thrice with 1 L of 2% NaOH, and then washedthrice with 1L of water. Thereafter the solution was passed at roomtemperature through a column made using 20 g of activated alumina(manufactured by Wako Pure Chemical Industries, Ltd.). The resultingorganic layer was concentrated under reduced pressure. The resultingproduct was vacuum dried with heating at 80° C. for 11 hours under 4 hPaor lower to obtain 228 g of a white powder.

The resulting crosslinked phenoxyphosphazene compound had an acid valueof 0.02 mg KOH/g and contained hydrolyzable chlorine of 0.03%. Fromphosphorus content and CHN elemental analytical values, the compositionof the final product was determined to be [N=P(—O—C₆H₄—C(CH₃)₂—C₆H₄—O—)_(0.25)(—O—C₆H₅)_(1.5)]. The weight-averagemolecular weight (Mw) in terms of polystyrene (according to GPCanalysis) was 1,140, a clear melting point was not shown by TG/DTAanalysis, the decomposition starting temperature was 311° C., and the 5%weight loss temperature was 322° C. Furthermore, as a result of carryingout the determination of residual hydroxyl group by an acetylationmethod, it was less than the limit of detection (less than 1×10⁻⁶equivalent/g as hydroxyl equivalent per 1 g of sample).

Reference Example 2: Preparation of a Phenoxyphosphazene Compound HavingCrosslinked Structure Given by 2,2-bis(p-oxyphenyl)isopropylidene Group

A crosslinked phenoxyphosphazene compound was prepared in the samemanner as in Preparation Example 2, except that the column treatmentwith activated alumina was not carried out in the post-treatment afterthe reaction, and as a result, 229 g of a white powder was obtained. Theresulting crosslinked phenoxyphosphazene compound had an acid value of0.55 mg KOH/g and contained hydrolyzable chlorine of 0.08%. Fromphosphorus content and CHN elemental analytical values, the compositionof the final product was determined to be [N═P (—O—C₆H₄—C(CH₃)₂—C₆H₄—O—)_(0.25)(—O—C ₆H₅)_(1.50)]. The weight-average molecularweight (Mw) in terms of polystyrene (according to GPC analysis) was1,100, a clear melting point was not shown by TG/DTA analysis, thedecomposition starting temperature was 306° C., and the 5% weight losstemperature was 312° C. Furthermore, as a result of carrying out thedetermination of residual hydroxyl group by an acetylation method, itwas less than the limit of detection (less than 1×10⁻⁶ equivalent /g ashydroxyl equivalent per 1 g of sample).

Preparation Example 3: Preparation of a Phenoxyphosphazene CompoundHaving Crosslinked Structure Given by 4,4-sulfonyldiphenylene(Bisphenol-S Residue)

32.9 Grams (0.35 mole) of phenol and 400 mL of THF were charged in a 1 Lfour-necked flask, and 0.30 gram atom (6.9 g) of metallic sodium chipswere added thereto under stirring while keeping the inner liquidtemperature at 25° C., followed by stirring at 65-72° C. for 5 hoursuntil the metallic sodium completely disappeared, thereby to prepare asodium phenolate solution.

In parallel with the above reaction, 160.0 g (1.70 mole) of phenol and12.5 g (0.05 mole) of bisphenol-S were dissolved in 500 mL of THF in a 1L four-necked flask, and 1.8 gram atom (41.4 g) of metallic sodium wasintroduced thereinto at 25° C. or lower. After completion of theintroduction, the temperature was raised to 63° C. over a period of 1hour, followed by continuation of stirring at 63-68° C. for 6 hours toprepare a sodium phenolate mixed solution. This solution was addeddropwise to 580 g of a 20% chlorobenzene solution containing 1.0 unitmole (115.9 g) of a dichlorophosphazene oligomer (concentration: 37%;chlorobenzene solution: 313 g; composition: a mixture of 70% of trimer,19% of tetramer, 8% of pentamer and hexamer, 2% of heptamer, and 1% ofoctamer or higher polymers) while keeping the inner liquid temperatureat 25° C. or lower, followed by carrying out the reaction with stirringat 71-73° C. for 5 hours. Then, the sodium phenolate mixed solutionprepared above was added dropwise, followed by continuing the reactionat 71-73° C. for 5 hours.

After completion of the reaction, the reaction mixture was concentratedand re-dissolved in 500 mL of chlorobenzene and was washed thrice with a5% aqueous NaOH solution, washed with 5% sulfuric acid, washed with a 5%aqueous sodium bicarbonate solution and washed thrice with water. Then,5 g of active carbon (CARBORAFIN manufactured by Takeda ChemicalIndustries, Ltd.) was added thereto, followed by stirring at roomtemperature for 1 hour. The active carbon was filtered off, followed byconcentrating to dryness to obtain 217 g of a white powder.

The resulting crosslinked phenoxyphosphazene compound had an acid valueof 0.01 mg KOH/g and contained hydrolyzable chlorine of 0.01% or less.From phosphorus content and CHN elemental analytical values, thecomposition of the compound was determined to be nearly[N=P(—O—C₆H₄,—SO₂—C₆H₄—O—)_(0.05)(—O—C₆H₅)_(1.90)]. The weight-averagemolecular weight (Mw) in terms of polystyrene (according to GPCanalysis) was 1,080, the melting point (Tm) according to TG/DTA analysiswas 105° C., the decomposition starting temperature was 323° C., and the5% weight loss temperature was 337° C. Furthermore, as a result ofcarrying out the determination of residual hydroxyl group by anacetylation method, it was less than the limit of detection (less than1×10⁻⁶ equivalent/g as hydroxyl equivalent per 1 g of sample).

Reference Example 3: Preparation of a Phenoxyphosphazene Compound HavingCrosslinked Structure Given by 4,4-sulfonyldiphenylene (Bisphenol-SResidue)

A crosslinked phenoxyphosphazene compound was prepared in the samemanner as in Preparation Example 3, except that the treatment withactive carbon was not carried out in the post-treatment after thereaction, and, as a result, 219 g of a citrine solid was obtained. Theresulting crosslinked phenoxyphosphazene compound had an acid value of0.56 mg KOH/g and contained hydrolyzable chlorine of 0.03% or less. Fromphosphorus content and CHN elemental analytical values, the compositionof the product was determined to be nearly[N=P(—O—C₆H₄—SO₂—C₆H₄—O—)_(0.05)(—O—C₆H₅)_(1.90)]. The weight-averagemolecular weight (Mw) in terms of polystyrene (according to GPCanalysis) was 1,060, the melting point (Tm) according to the TG/DTAanalysis was 103° C., the decomposition starting temperature was 318°C., and the 5% weight loss temperature was 331° C. Furthermore, as aresult of carrying out the determination of residual hydroxyl group byan acetylation method, it was less than the limit of detection (lessthan 1×10⁻⁶ equivalent/g as hydroxyl equivalent per 1 g of sample)

Preparation Example 4: Preparation of Phenoxyphosphazene Compound Havinga Crosslinked Structure Given by p-phenylene

A mixture of 94.11 g (1.0 mole) of phenol, 40.0 g (1.0 mole) of sodiumhydroxide, 50 g of water and 500 mL of toluene was refluxed underheating to remove only water out of the system, thereby to prepare atoluene solution of sodium phenolate.

In parallel with the above reaction, a mixture of 16.5 g (0.15 mole) ofhydroquinone, 94.1 g (1.0 mole) of phenol, 31.1 g (1.3 mole) of lithiumhydroxide, 52 g of water and 600 mL of toluene was charged in a 2Lfour-necked flask and refluxed under heating to remove only water out ofthe system, thereby to prepare a toluene solution wherein lithium saltof phenol and that of hydroquinone are dissolved. To this toluenesolution was added dropwise 580 g of a 20% chlorobenzene solutioncontaining 1.0 unit mole (115.9 g) of a dichlorophosphazene oligomer(concentration: 37%; chlorobenzene solution: 313 g; composition: amixture of 70% of trimer, 19% of tetramer, 8% of pentamer and hexamer,2% of heptamer, and 1% of octamer or higher polymers) at 30° C. orlower, followed by carrying out the reaction with stirring at 110° C.for 5 hours. Then, the toluene solution of sodium phenolate preparedabove was added, followed by continuing the reaction at 110° C. for 5hours.

After completion of the reaction, the reaction mixture was washed thricewith 1.0 L of a 3% aqueous sodium hydroxide solution, then washed with1.0 L of water thrice. After vacuum distilling off toluene, the reactionmixture was vacuum dried with heating at 120° C. for 11 hours under 4hPa or lower. To the resulting melt containing no solvent was added 5 gof activated clay (tradename: GAREONEARTH V2 manufactured by MizusawaIndustrial Chemicals, Ltd.), followed by stirring at 120° C. for 1 hour.After the activated clay was filtered off with heating, the melt wascooled to obtain 209 g of a white powder.

The resulting crosslinked phenoxyphosphazene compound had an acid valueof 0.01 mg KOH/g and contained hydrolyzable chlorine of 0.02%. Fromphosphorus content and CHN elemental analytical values, the compositionof the final product was determined to be[N=P(—O—p—C₆H₄—O—)_(0.15)(—O—C₆H₅)_(1.70)]. The weight-average molecularweight (Mw) in terms of polystyrene (according to GPC analysis) was1,090, no clear melting point was shown according to TG/DTA analysis,the decomposition starting temperature was 309° C., and the 5% weightloss temperature was 312° C. Furthermore, as a result of carrying outthe determination of residual hydroxyl group by an acetylation method,it was less than the limit of detection (less than 1×10⁻⁶ equivalent/gas hydroxyl equivalent per 1 g of sample).

The phosphoric acid ester flame-retardants used in the comparativeexamples are as follows.

TPP: Triphenyl phosphate having an acid value of 0.03 mg KOH/g (TPPmanufactured by Daihachi Chemical Industry Co., Ltd.).

BPA-DPP: A phosphoric acid ester compound mainly composed of bisphenolA-bis(diphenyl phosphate) having an acid value of 0.6 mg KOH/g (CR-741manufactured by Daihachi Chemical Industry Co., Ltd.).

Evaluation of physical properties of the resin compositions of theexamples and the comparative examples was conducted by the followingmethods and under the following conditions.

(1) Flame retardancy:

This was measured according to UL-94 vertical flame test, using a testpiece of {fraction (1/16)} inch in thickness made by injection molding,and evaluation was conducted on total burning time when the test piecewas allowed to contact with a flame 10 times and on whether dropping ofmaterials occurred or not during burning.

(2) Electrical characteristics:

A molded test piece of 150×150 mm with a thickness of about 2 mm wasleft to stand for 200 hours at 90° C. in a thermo-hygrostat (ModelPL-3FP manufactured by TABAI ESPEC COP.) set at a relative humidity of95%, and then left to stand for 24 hours at 23° C. in a constanttemperature and humidity room of 50% in relative humidity, andsubsequently the electrical characteristic (dielectric loss tangent) ofthis test piece was measured at frequencies of 100 hertz (Hz) and 1megahertz (MHz).

(3) Izod impact strength (IZOD):

This was measured in accordance with ASTM D-256.

(4) Deflection temperature under load (DTUL):

This was measured in accordance with ASTM D-648.

(5) Deposition on mold:

Degree of deposition of the flame-retardant on the mold during injectionmolding was judged by the degree of clouding of the mold surface due tothe short shot when a test piece for testing of physical properties wasmolded. When substantially no clouding occurred, this is indicated by“∘”, when slight clouding occurred, this is indicated by “Δ”, and whenheavy clouding occurred, this is indicated by “X”.

Examples 1-6 and Comparative Examples 1-5

The components were mixed at the ratio as shown in Table 1, and themixture was fed to a twin-screw extruder of 25 mm in screw diameter witha setting of the maximum temperature of the heating cylinder at 320° C.and melt kneaded at a screw revolution speed of 300 rpm, followed bycooling and cutting the strands to obtain pellets of the resincomposition. Then, the resulting pellets of resin composition wereinjection molded at 240-290° C. to prepare a test piece for testing ofphysical properties, which was subjected to physical property tests bythe above-mentioned test methods to obtain the results as shown inTable 1. No dropping of materials during burning was seen in any of theExamples and Comparative Examples.

TABLE 1 Example Comparative Example 1 2 3 4 5 6 1 2 3 4 5 PPE (part byweight) 40 40 40 70 40 40 40 40 40 40 40 HIPS (part by weight) 35 35 3921 39 39 35 39 39 39 39 Phosphazene compound (part by weight)Preparation Example 1-1 (acid value: 0.01) 15 Preparation Example 1-2(acid value: 0.3) 15 Preparation Example 2 (acid value: 0.02) 11  9Preparation Example 3 (acid value: 0.01) 11 Preparation Example 4 (acidvalue: 0.01) 11 Reference Example 1 (acid value: 0.77) 15 ReferenceExample 2 (acid value: 0.55) 11 Reference Example 3 (acid value: 0.56)11 Phosphoric acid ester flame-retardant (part by weight) TPP (acidvalue: 0.03) 11 BPA-DPP (acid value: 0.6) 11 Physical properties Flameretardancy 40 47 48 37 46 44 78 89 78 58 82 Total buring time in secondsElectrical characteristics Dielectric loss tangent (100 Hz) 0.00110.0017 0.0010 — — — 0.0042 0.0038 — 0.0046 0.0041 Dielectric losstangent (1 MHz) 0.0014 0.0021 0.0012 — — — 0.0048 0.0030 — 0.0058 0.0031IZOD (Kg · cm/cm) 11 10 12 13 12 13 10 12 11 13 10 DTUL (° C.) 98 98105  141  108  107  97 105  107  83 96 Deposition onto mold ◯ ◯ ◯ ◯ ◯ ◯Δ Δ Δ X Δ

Industrial Applicability

The present invention provides a resin composition which contains nohalogen-containing compounds, is excellent in electricalcharacteristics, heat resistance and mechanical properties, causessubstantially no problems such as occurrence of smoke during injectionmolding and deposition of flame-retardants on the mold, is desirable forenvironmental health, and has high flame retardancy.

What is claimed is:
 1. A resin composition which contains (A) a resincomposition comprising a polyphenylene ether resin or a polyphenyleneether resin and a polystyrene resin and (B) a phosphazene compoundhaving an acid value of less than 0.5.
 2. A resin composition accordingto claim 1, wherein the acid value of the phosphazene compound is lessthan 0.3.
 3. A resin composition according to claim 1 or 2, wherein thephosphazene compound is a phenoxyphosphazene compound.
 4. A resincomposition according to claim 1 or 2, wherein the phosphazene compoundhas a cyclic structure.
 5. A resin composition according to claim 1 or2, wherein the phosphazene compound is a phenoxyphosphazene compoundhaving a crosslinked structure.